A method and a computer readable medium includes instructions for obtaining time data as programmed into processing recipes or as recorded when a wafer is processed and transferred during lithography operations. The data is parsed and saved into an MES database. A report server accesses the database responsive to a query made of the database. A query may specify one or more fabrication parameters. The specified fabrication parameter or parameters is fixed and a data display is provided that compares times for processing and transferring wafers in various lithography operations used in the production of the semiconductor device and bottlenecks in lithography operations are identified by the comparative data.
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1. A method for comparing lithography processing time data in semiconductor device manufacturing, said method comprising:
obtaining wafer time log data from each of a plurality of lithography tools, said wafer time log data including times observed, measured and recorded at processing operations;
parsing said wafer time log data;
providing said wafer time log data to a database;
querying said database by specifying at least one fixed fabrication parameter of a plurality of fabrication parameters;
classifying said wafer time log data according to at least another one of said plurality of fabrication parameters and responsive to said querying; and
identifying at least one lithography operation bottleneck based on said wafer time log data in said database, by generating a data display that identifies said at least one lithography operation bottleneck by comparing operation time data between at least one other of said fabrication parameters, said operation time data including wafer processing times and wafer transport times.
16. A computer readable medium with encoded instructions for performing a method for identifying lithography processing bottlenecks in semiconductor device manufacturing, the method comprising the operations of:
obtaining wafer time log data from each of a plurality of lithography tools, said wafer time log data including times observed, measured and recorded at processing operations;
parsing said wafer time log data;
providing said wafer time log data to a database;
correlating said wafer time log data;
receiving a query made of said database, said query specifying and fixing at least a first fabrication parameter of a plurality of fabrication parameters;
classifying said wafer time log data according to at least another one of said plurality of fabrication parameters and responsive to said query; and
identifying at least one lithography operation bottleneck based on said wafer time log data in said database, by generating a data display that identifies said at least one lithography operation bottleneck by comparing operation time data between at least one other of said fabrication parameters, said operation time data including wafer processing times and wafer transport times.
15. A method for identifying lithography operation bottlenecks in semiconductor device manufacturing, said method comprising:
obtaining wafer time log data from at least one lithography tool, said wafer time log data including times observed, measured and recorded at processing operations;
parsing said wafer time log data;
providing said wafer time log data to a database;
querying said database by specifying at least one fixed fabrication parameter of a plurality of fabrication parameters;
classifying said wafer time log data according to at least another one of said plurality of fabrication parameters and responsive to said querying; and
identifying at least one lithography operation bottleneck based on said wafer time log data in said database, by generating a data display that identifies said at least one lithography bottleneck by comparing operation time data between other of said fabrication parameters, said operation time data including average wafer processing times and average wafer transport times,
said wafer time log data including processing and transport times for individual components of each said lithography tool, said individual components including wafer coaters, cooling plates, developer heads, hard bake units, soft bake units, post- exposure bake units, exposure, and adhesion treatment.
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The present invention relates, most generally, to data analysis software and methods for manufacturing semiconductor devices. More particularly, the present invention is related to a method and software for analyzing processing and transport times associated with lithography operations in semiconductor manufacturing, and for querying a database to produce comparative time data that reveals bottlenecks in such lithography operations.
Semiconductor device manufacturing involves a lengthy fabrication process that includes multiple patterning operations. Each of the patterning operations utilizes a photolithographic process sequence. The photolithographic process sequence involves coating a wafer with a photosensitive material such as photoresist, then forming a pattern in the photosensitive material. The pattern is formed in the photosensitive material by first exposing the photosensitive material to light that has been directed through a photomask which has an opaque pattern, then developing the photosensitive material to remove the exposed or unexposed portion of the film, depending on whether positive or negative photosensitive material is used. Such a pattern is found at several device levels in the manufacture of a semiconductor device.
These operations are carried out along with several other operations in an integrated lithography tool that typically includes a stepper or scanner within which the exposure operation is carried out, and a track that includes multiple units that perform the previously discussed develop and coat operations as well as hard bake operations, soft bake operations, cooling operations, adhesion enhancement operations, post-exposure bake operations and requisite wafer transfer operations between the stations. There are therefore processing times associated with each of the aforementioned unit operations including wafer-to-wafer transfer times between the unit operations. Moreover, the time required to process an entire lot through a unit operation is influenced by the number of units used to carry out the operation. For example, in a single lithography tool, there may be multiple coating operations, multiple hard bake stations, multiple developer heads, and so forth. When a lot of semiconductor wafers has completed processing at the lithography operation, and a new lot is poised to be processed at the lithography tool, the recticle or photomask must be changed. As such, there are also lot-to-lot set up transfer times to consider.
High volume semiconductor manufacturing facilities typically have several of the aforementioned lithography tools and each of the lithography tools may be used to carry out patterning operations at various different levels for various different technologies and device types. Many process recipes may be used to carry out the patterning operations using the various unit operations described above, and the recipes typically vary by device level. Moreover, the number of unit operations may be different for the various lithography tools in a production facility.
In today's rapidly advancing semiconductor manufacturing industry, the time required to process a semiconductor wafer at any stage such as the patterning operations, is critically important. A reduction in processing time at any particular processing operation produces an increased WPH (wafers per hour) output for the processing tool and this increased manufacturing tool output improves the efficiency of the tool producing a cost savings. Each processing tool such as a lithography tool may typically include an inherently time limiting operation such as the alignment and exposure operation in a lithography tool. It would be inefficient and cost ineffective to have an overall lithography operation limited by a different operation, for example a baking operation that requires more time than the exposure operation due to an insufficient number of bake plates or other process inefficiencies associated with the baking operation. Such would be a bottleneck that hinders overall progress at the lithography operation.
It is therefore critically important to quickly identify bottlenecks in lithography operations. Moreover, it would be advantageous to specify one fabrication parameter such as lithography tool or technology type, device type, device level, or reticle and to be able to quickly compare processing times between other of the fabrication parameters.
To address these and other needs and in view of its purposes, the present invention provides a method for comparing lithography processing time data in semiconductor device manufacturing. The method includes obtaining wafer time log data from each of a plurality of lithography tools, parsing the wafer time log data and providing the wafer time log data to a database. The method also includes querying the database by specifying at least one fixed fabrication parameter of a plurality of fabrication parameters, classifying the wafer time log data according to other of the fabrication parameters and responsive to the querying, and generating a data display that identifies at least one lithography operation bottleneck by comparing operation time data between at least one other of the fabrication parameters. The operation time data includes wafer processing and wafer transport times.
According to another aspect, the present invention provides a method for identifying lithography operation bottlenecks in semiconductor device manufacturing. The method includes obtaining wafer time log data from at least one lithography tool, parsing the wafer time log data and providing the wafer time log data to a database. The method also includes querying the database by specifying at least one fixed fabrication parameter of a plurality of fabrication parameters and classifying the wafer time log data according to other of the fabrication parameters and responsive to the querying. The method further includes identifying at least one lithography operation bottleneck by generating a data display based on the wafer time log data in the database that identifies at least one of the lithography operation bottlenecks by comparing operation time data between the other fabrication parameters. The operation time data includes average wafer processing times and average wafer transport times. The wafer time log data includes processing and transport times for individual components of each lithography tool, the individual components including wafer coater, cooling plates, developer heads, hard bake units, soft bake units, post exposure bake units, exposure operation and adhesion treatment.
According to another aspect, the invention provides a computer readable medium with encoded instructions for performing a method for identifying lithography operation bottlenecks in semiconductor device manufacturing. The method may be one of the aforementioned exemplary methods.
The present invention is best understood from the following detailed description when read in conjunction with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not necessarily to scale. On the contrary, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. Like numerals denote like features throughout the specification and drawing.
The invention provides a versatile diagnostic tool including a system, software and a method for obtaining wafer time log data such as times observed, measured or recorded at semiconductor processing operations including process time and transfer time, and also programmed times for the various process recipes used in photolithographic processing operations. Such wafer time log data is recorded for multiple lithographic tools in a fabrication area, multiple technologies, multiple device types, multiple recipes, and at multiple device levels. This data covers multiple lots. A lot is a group of wafers that are transported and processed together through a fabrication area. The wafer time log data is also obtained for processing sub-units, that is individual processing operations carried out in conjunction with the lithography process, such as various bakes, coat operations, develop operations, and so forth. The data is compiled into a database and classified according to data type. A user queries the database by specifying at least one parameter and in response to the querying, the data is correlated, reorganized and classified and a diagnostic display is provided. The diagnostic display presents operation time data comparing various processing operations, fabrication parameters and units. Such comparative data displays may identify a bottleneck in the system. A bottleneck is used in its ordinary meaning and may be considered a delay in progress caused when one part of the operation or activity is slower than the others and so hinders overall progress. The operation time data may be provided in tabular or chart form and may express the time data in WPH (wafers per hour) or in other suitable time units.
Based on the identified lithography operation bottleneck or bottlenecks, one or more changes may then be instituted in one or more processing operations of the semiconductor device manufacturing operation. For example, a processing tool may be examined and a mechanical, programming or other adjustment may be made to upgrade or correct a problem in the processing tool. The processing tool may be a lithography or other manufacturing tool. Engineering changes may be instituted to improve the performance of a tool or a component thereof. The capacity of a tool may be increased. An additional tool may be obtained and/or qualified for use for a particular operation or to run a particular recipe. The product mix running through a particular tool may be altered to reduce backlog, e. g., if a bottleneck occurs while running a high volume of product 1 that requires step x, in tool a, product starts may be altered to include more product 2, that does not require step x, or does not require tool a. The foregoing examples are intended to illustrate and not limit the changes that may be made responsive to the identified bottlenecks.
Lithography tools 2 may be any suitable lithography tools used in semiconductor manufacturing, in particular, lithography tools 2 may be any of various steppers or scanners, such as may be manufactured by ASML of Velvhoven, the Netherlands or other suitable manufacturers. Various other lithography tools such as ILSC (I-line scanners), DUV scanners and other suitable tools may be used in other exemplary embodiments. Lithography tools 2 are each electronically coupled to computer system 4 to enable communication therebetween. Although the illustrated embodiment shows three (3) such lithography tools 2, the system may accommodate any number of lithography tools 2 coupled to computer system 4. Each lithography tool 2 includes an exposure area in which a wafer is exposed, and lithography tool 2 also includes a plurality of sub-units and transport units that transport the wafers to and between the sub-units according to a process recipe that may be programmed into lithography tool 2. The sub-units or individual components of lithography tool 2 may include one or more cooling plates, one or more photoresist coaters, one or more develop stations, one or more hard bake stations, one or more soft bake stations, one or more post exposure bake stations, and one or more adhesion enhancement stations, such as may be used to coat wafers with HMDS (hexamethyldisilizane). The number of sub-units or individual components of the lithography tool may vary. For example, the three illustrated lithography tools 2 may include different numbers of one or more of the aforementioned sub-units or individual components.
A wafer will be loaded into the transport system of lithography tool 2 and, according to a process recipe, will be processed through one or more of the aforementioned sub-units and in various sequences also prescribed by the recipe. The time and conditions for processing at each of the sub-units is prescribed by the associated recipe. Various different device types, various different process technologies and various different process levels or reticle levels, may be processed in each lithography tool 2 using various recipes. The wafer time log data that is provided to computer system 4 includes programmed times for each operation that takes place in each of the sub-units or individual components such as provided on a recipe. The wafer time log data provided to computer system 4 also includes observed and recorded times for processing wafers in processing operations that are not time-programmed, such as exposure operations which are programmed for exposure amount and for which time is a dependent variable. The wafer time log data provided to computer system 4 also includes times for transporting wafers. Transport times include wafer-to-wafer transfer times at a particular sub-unit, station-to-station transfer times and lot-to-lot set up and transfer times.
Still referring to
TP2 server 14 is programmed with code that causes TP2 server 1 to obtain and parse TP2 wafer data log file information from the raw data files of TP2 log files 15 at IPC's 13. TP2 server 14 may include an NT server platform with SECS interface. The development program used may be Delphi 5.0, but other suitable development programs may be used. In one exemplary embodiment, the TP2 server 14 may be an Intel-based PC with an MS Windows 2003 operating system but other systems may be used in other exemplary embodiments. TP2 server 14 may be an NT Server 2003 but other suitable servers may be used in other exemplary embodiments. Such parsed wafer operation information is extracted and stored in MES database 18 which includes all MES (Manufacturing Execution Systems) data and TP2 data. IBM DB2/UDB v7.2 software may be used in one exemplary embodiment but other software products may be used in other exemplary embodiments. MES host 16 extracts the TP2 data from relational MES database 18, processes the data, summarizes the data and returns the data to MES database 18. MES host 16 may be programmed using java, C/C++, SQL or other suitable programming languages. MES database 18 data is obtained by report server 20 which processes the database data.
Report server 20 is a J2EE application server running as a presentation system. Report server 20 obtains the query input and serves the interface unit 8. In one exemplary embodiment, a J2EE application server may use a BEA Web Logic version 81 software. The J2EE application server provides a user interface at user interface unit 8 such as is shown in
Computer system 4 performs operations for obtaining, correlating, classifying, i.e. arranging or ordering by class or category, comparing and presenting the data. Another aspect of the invention is a computer program product with encoded instructions for performing operations for managing data in a database, in particular identifying lithography processing bottlenecks in semiconductor device manufacturing. The computer readable medium is encoded with computer program code, wherein, when the computer program code is executed by a computer processor in computer system 4, the processor formed of the platforms of IPCs 13, TP2 server 14, MES host 16 and Report Server 20 performs a method for obtaining, correlating, classifying, comparing and presenting data and for identifying lithography processing bottlenecks in semiconductor device manufacturing. The method includes the steps of obtaining wafer time log data from multiple lithography tools and providing the wafer time log data to a database such as MES database 18. Computer system 4 then correlates the wafer time log data as described previously. Computer system 4 receives a query of the database via HTTP link 6 and interface 8. The query specifies and fixes at least one fabrication parameter. The wafer time log data is classified by MES host 16 which pre-summarizes the data according to other fabrication parameters and responsive to the querying. Report server 20 then generates a WPH (wafer per hour) data presentation that identifies at one lithography processing bottleneck by comparing operation time data between the other fabrication parameters. The operation time data includes wafer processing times and wafer transport times.
A user queries MES database 18 using interface unit 8 to obtain a display of data 12 that may be displayed on display screen 10 and which compares aspects of the lithography operations and identifies bottlenecks. An exemplary interface screen will be shown in
Data 12 may be presented in various forms such as tables, charts and graphs and may be used to illustrate comparisons between process parameters with one or more other process parameters fixed. For example, a process recipe and particular device type may be selected and fixed, and the data display will illustrate comparisons in processing and transfer time, between different processing tools 2. User interface unit 8 may provide, responsive to a user's query, a photolithography wafer WPH report, a photolithography wafer WPH detail report, a tool-to-tool WPH comparison for one particular reticle, a tool-to-tool key indices comparison for an ILSC, I-line Scanner, or other lithography tools, a tool operation history report with photolithography WPH, a track bottleneck unit for a GPS or other transport method, and other similar reports displayed variously.
Table 50 of
The preceding merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes and to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.
This description of the exemplary embodiments is intended to be read in connection with the figures of the accompanying drawing, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures or components are secured or attached to one another either directly or indirectly through intervening structures or components, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.
Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention, which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.
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